Photo-induced halide redistribution in organic–inorganic perovskite films

• Published in: Nature communications Vol. 7; no. 1; p. 11683
• Main Authors: deQuilettes, Dane W., Zhang, Wei, Burlakov, Victor M., Graham, Daniel J., Leijtens, Tomas, Osherov, Anna, Bulović, Vladimir, Snaith, Henry J., Ginger, David S., Stranks, Samuel D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.05.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 140/125; 639/301/299; 639/624/1075/401; 639/766/400; anomalous hysteresis; Calcium Compounds - chemistry; Calcium Compounds - radiation effects; CH3NH3PbI3; diffusion; electron; Humanities and Social Sciences; Iodides - chemistry; Iodides - radiation effects; Iodine; Iodine - chemistry; Iodine - radiation effects; Lead - chemistry; Lead - radiation effects; lead-iodide; Lifetime; Light; Luminescent Measurements - methods; Mass spectrometry; MATERIALS SCIENCE; Methylamines - chemistry; Methylamines - radiation effects; Microscopy; Microscopy, Confocal - methods; multidisciplinary; Oxides - chemistry; Oxides - radiation effects; photoluminescence; recombination; Science; Science (multidisciplinary); Scientific imaging; single-crystals; solar-cells; Spectrometry, Mass, Secondary Ion - methods; thin-films; Titanium - chemistry; Titanium - radiation effects; United Kingdom > UK; United States > US; Massachusetts
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms11683

Organic–inorganic perovskites such as CH 3 NH 3 PbI 3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH 3 NH 3 PbI 3 films under illumination. We demonstrate that the photo-induced ‘brightening’ of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance. Visual evidence for photo-induced ionic migration in perovskite films without contacts is lacking. Here, the authors use a unique combination of confocal photoluminescence microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH 3 NH 3 PbI 3 films under illumination.